Reactive bio-based flame retardant derived from chitosan, phytic acid, and epoxidized soybean oil for high-performance biodegradable foam

Due to the shortage of global petrochemical resources, preparing biodegradable polyurethane foam (PUF) with excellent strength and resistance against fire is an important way for sustainable development. A reactive all bio-based flame retardant CPE was prepared using chitosan (CS), phytic acid (PA), and epoxidized soybean oil (ESO) as raw materials. Meanwhile, the bio-based PUF matrix, named ERP, was prepared with ESO, ricinoleic acid (RA) and 4,4-diphenylmethane diisocyanate (PMDI). Thus, ERPC-EG foam with excellent performance was prepared by blending ERP, CPE flame retardant and expandable graphite (EG). The crosslinking of ESO with CS and PA effectively improved the hydrophobicity of CPE flame retardants. Furthermore, the LOI value of ERPC-EG foam is an exceptional 33.5 vol%. In addition, it attains V -0 classification in the UL-94 vertical combustion test, exhibiting excellent flame retardancy. Its peak heat release rate (pHRR) and total smoke release (TSP) during combustion are 99.42 kW/m 2 and 0.91 m 2 , respectively, demonstrating effective smoke suppression capabilities. ERPC-EG foam exhibited a mass loss of 2.35 % following a 60-day burial in soil, indicating its biodegradable nature. This study presents a technique for creating biodegradable polyurethane foam with superior flame retardant properties.